HiCustomer The valve body contains all the shift solenoids and most of the electronics for the trans. It is not hard to replace for an experienced tech, but may be difficult for someone who has not done it before. The most critical part is torquing the new valve body down, and lining it up. It is located above the trans pan. I do not recommend this for a beginner. I have attached the directions.
HiCustomer I have double checked the Ford website and have found they have superseded the old TSB with a new one. I would just replace the solenoid pack, it is easier and cheaper. The valve body you have should be the updated one. If you do need to change the valve body later, you will just lose on the labor, but if you are doing it yourself, it should be no big deal. The solenoid pack can be replaced in a couple of hours. I have attached the TSB.